1. Field of the Invention
The present invention pertains, in general, to a batch-type polyester polymerization apparatus and in particular, to a batch-type polyester polymerization apparatus, which is manufactured by assembling a conventional batch-type apparatus with a thin film tower.
2. Description of the Prior Art
As well known to those skilled in the art, a conventional method of producing polyester comprises the steps of an ester reaction of aromatic diacid with aliphatic or alicyclic glycol, or an ester exchange reaction of low molecular weight alkyl ester of aromatic diacid with aliphatic or alicyclic glycol to produce low molecular weight oligomer; and a polymerization of the oligomer. At this time, the oligomer is polymerized in the presence of a polycondensation catalyst at a temperature of 280° C. or higher under vacuum while continuously removing water and aliphatic glycol to produce polyester with a desirable degree of polymerization.
However, the conventional method is disadvantageous in that the polymerization of the oligomer is conducted at a relatively high temperature and it is difficult to sufficiently agitate the oligomer during the polymerization, thus reducing polymerization efficiency of the oligomer to undesirably extend polymerization time and reduce productivity of polyester.
Many efforts have been made to avoid the above disadvantages. For example, Japanese Patent Laid-Open Publication No. Hei. 09-268231 discloses a method of polymerizing low molecular weight oligomer by spraying it onto a roller under vacuum to produce a polyester sheet, Japanese Patent Laid-Open Publication No. Hei. 01-040080 discloses a method of polymerizing low molecular weight oligomer by spraying it onto a drum under vacuum to produce a polyester film. Other conventional methods are suggested in Japanese Patent Laid-Open Publication No. Sho. 63-104602 in which oligomer is polymerized while being spouted through slits or circular holes to produce polyester sheets or rods, and in Japanese Patent Publication No. Hei. 05-053815 in which oligomer is polymerized while falling freely in a long vertical polymerization tower.
However, these conventional methods produce polyester according to a continuous polymerization process using an undesirably large device, thus causing many problems in their commercialization.